JPH0762446B2 - Silencer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a silencer for silencing exhaust noise generated from an automobile engine or the like, and in particular has low resistance to the flow of exhaust gas and is extremely efficient. The present invention relates to a silencer that can be effectively silenced.

(Prior Art) There have been various types of silencers for silencing exhaust noise generated from an engine for automobiles, etc. Conventionally, there are various types of silencers, as shown in FIG. An exhaust pipe 1'and a tail pipe 2'at the other end are displaced and attached, and the inside of a cylindrical silencer body 3'is divided into a plurality of chambers 5a, 5b, 5c by partition walls 4, 4, and both partition walls 4 ' The exhaust pipe 1'is attached to one end so as to pass through the holes 4 and 4, and is opened to the chamber 5c, and the tail pipe 2 is attached to the other end so as to cross each other and opened to the chamber 5a. In the intermediate position of the above, these chambers 5a, 5b, 5c are communicated with each other by two intermediate conduits 6 ', 6'through the partition walls 4, 4 and a large number of them are provided on the peripheral wall of the portion located in the main body of the exhaust conduit 1'. The small holes 7 of the exhaust gas are provided, and the resistance and gas when exhaust gas passes through these small holes 7 There was a type that silenced depending on the resistance when the flow was reversed and the capacity of the chambers 5a, 5b, 5c.

(Problems to be solved by the invention) In order to improve the efficiency of the engine, it is desirable that the exhaust resistance of the exhaust system is as small as possible. However, if the exhaust resistance is reduced, the exhaust system causes a resonance phenomenon and the exhaust of a specific frequency is exhausted. There was a problem that the sound could not be silenced.

Conventionally, as shown in FIG. 21, the exhaust gas is passed through a large number of small holes 7 or the gas flow is reversed to increase the exhaust resistance, thereby preventing the resonance phenomenon. However, the increase in exhaust resistance naturally causes a decrease in engine efficiency, and is not always satisfactory.

Resonance phenomenon is a sound wave generated from the engine and traveling through the exhaust pipe, the silencer body, and the tail pipe.The traveling wave is reflected at the end of the tail pipe, becomes a reflected wave, interferes with the traveling wave, and strengthens the sound. It is a phenomenon that meets each other, that is, a phenomenon in which sound energy is accumulated.

Therefore, to prevent this resonance phenomenon, sound energy should be absorbed somewhere in the exhaust pipe, silencer body, or tail pipe to prevent energy accumulation. It is not preferable to install a resistor in the main flow path of the exhaust gas, such as the main body and the tail pipe, and to absorb the energy, because this increases the exhaust resistance of the exhaust gas and must be avoided.

The present invention is based on a principle completely different from the conventional silencer, and provides a silencer capable of preventing a resonance phenomenon without increasing exhaust resistance and efficiently reducing engine exhaust noise. The purpose is.

[Structure of the Invention] (Means for Solving the Problems) The present invention reduces the exhaust resistance by causing the gas flow in the silencer body to flow in a substantially straight line without reversing, thereby reducing the exhaust resistance, the intermediate conduit, By providing an inner pipe having a plurality of resistors through which gas can pass inside the tail pipe, or by providing a bypass passage that branches off from the upstream side of the exhaust pipe or the tail pipe, and providing a resistor in this bypass passage. This solves the conventional problem associated with the muffler.

(Operation) The silencer of the present invention is as described above, and the exhaust gas sent from the engine through the exhaust conduit is shunted into the main flow path and the bypass path, and a part of the traveling wave and the tail pipe terminal end are separated. A part of the reflected wave reflected is propagated to the bypass path, and the sound wave energy is absorbed in this bypass path, so that the accumulation of sonic energy and the accompanying resonance phenomenon are prevented, and the exhaust sound generated by the engine is It is muted.

(Embodiment) FIG. 1 shows a first embodiment of the present invention, in which a tail pipe 2 is attached to the other end of a silencer body 10 having an exhaust conduit 1 at one end. The exhaust pipe 1 has a large diameter portion 1 ″ on the silencer body 10 side and a large diameter portion 2 ″ on the tail pipe 2 side of the silencer body.

The silencer body 10 is divided into a plurality of chambers 5a, 5b, 5c by a plurality of partition walls 4, 4, and these chambers 5a, 5a
Between b and 5c, short intermediate conduits 6,6 penetrating through the centers of both partition walls 4,4 are located in line with the exhaust conduit 1 and communicate with each other. Although the muffler body 10 of the first embodiment is divided into a plurality of chambers 5a, 5b, 5c, it is not always necessary to divide it into a plurality of chambers, for example, as shown in FIG. 6 may be connected to the large diameter portion 2 ″ of the tail pipe.

On the other hand, an inner pipe 12 is installed inside the large diameter portion 1 ″ of the exhaust pipe 1, the intermediate pipe 6 and the large diameter portion 2 ″ of the tail pipe 2,
It has a double pipe structure, and the inner pipe 12 has a plurality of support pieces 1
A main flow passage M, which is supported by the large diameter portions 1 ″, 2 ″ by 9, 19, ... And has no resistor, is formed between the exhaust conduit 1, the intermediate conduit 6 and the inner peripheral wall of the tail pipe 2. .

On the other hand, inside the inner tube 12, a plurality of resistors 14 having a passage hole 13 formed by an orifice in the central portion are attached at predetermined intervals to form a bypass passage B.

It is effective to attach 5 to 20 orifices to the resistor 14, and the aperture ratio of the passage hole 13 is 30% to 70%.
Is preferable, since the acoustic wave is reflected by the resistor 14 at an aperture ratio of less than that and the acoustic wave energy is not absorbed by the orifice, it is not desirable, and if it is more than that, a large number of resistors 14 are used to obtain the necessary resistance. Needed and uneconomical.

The resistor 14 is not limited to the orifice, and for example,
It may be a porous plate, a spiral plate, a wire mesh, a linear body, or a fibrous sound absorbing material such as glass wool.

The cross-sectional area of the inner pipe 12 forming the bypass B is preferably about the same as the cross-sectional area of the tail pipe 2, and the length of the inner pipe 12 is preferably 1/4 or more of the wavelength of the sound wave, but even about 1/16. It is possible to obtain an effect.

However, if the length is further shortened, the effect is lost. Therefore, at least three times the diameter of the tail pipe 2 is necessary.

Further, it is important that the main flow passage M and the bypass passage B are separated except at the branching point and the merging point, and that there is no transmission / reception of acoustic energy, and that the peripheral wall of the inner tube 12 is porous. Must be avoided.

In the case of a diesel engine in which dust is mixed in the exhaust gas, a resistor 14 is used to prevent dust from being accumulated in the inner pipe 12 as in the second embodiment shown in FIG. It is better to provide the passage hole 13 'provided below so as to contact the inner peripheral wall of the inner pipe 12.

Further, the shape of the passage holes 13 and 13 'of the resistor 14 is not necessarily limited to the circular shape, but may be a semicircular shape as in the third embodiment shown in FIG. 4, or may be another shape.

In each of the above-described embodiments, the exhaust gas introduced into the exhaust conduit 1 is discharged between the exhaust conduit 1 and the inner pipe 12, between the intermediate conduit 6 and the inner pipe 12, and between the tail pipe 2 and the inner pipe 12. A plurality of chambers 5a, 5b, 5c of the silencer body 10 are passed through the main flow path M.
And is discharged to the outside from the tail pipe 2.

A part of the exhaust gas is guided from the exhaust conduit 1 to the bypass passage B in the inner pipe 2, passes through each passage hole 13 of the resistor 14 and is discharged from the tail pipe 2 to the outside, but the gas flow rate through the main passage M. It is a small amount compared to. Since there is no resistance in the main flow path M through which most of the gas flows, the exhaust resistance is extremely small.

When the exhaust gas traverses the interior of the silencer body 10 or a plurality of chambers inside the silencer body 10, the acoustic waves of the exhaust gas are attenuated.

Generally, when the gas flow does not reverse in the silencer body 10 and the exhaust resistance is small, a resonance phenomenon occurs and the sound wave is not attenuated, but in the silencer of the present invention, the resistance provided in the inner pipe 12 The resonance phenomenon is prevented because the body 14 becomes a resistance to sound waves.

Next, FIGS. 5 and 6 show a fourth embodiment of the present invention, in which the main passage M and the bypass passage B are provided at the other end of the silencer body 10 having the exhaust conduit 1 at one end. Anti-resonance body
11 are connected in series, and the tail pipe 2 is attached to the end portion of the resonance preventing body 11.

The muffler main body 10 is partitioned into a plurality of chambers 5a, 5b, 5c by a plurality of partition walls 4, 4, and these chambers 5a, 5b
Between b and 5c, short conduits 6 and 6 penetrating through the centers of both partition walls 4 and 4 are located in line with the exhaust conduit 1 and communicate with each other. Also in this case, it is not always necessary to divide the chamber.

On the other hand, the resonance preventive body 11 connected to the muffler body 10 has a double pipe structure composed of an outer pipe 15 and an inner pipe 12, and an upper portion of the space between the outer pipe 15 and the inner pipe 12. 14 arc-shaped resistor
Are installed at predetermined intervals. A passage hole 13 is formed below the resistor 14. That is, in this embodiment, contrary to the first embodiment, the inside of the inner pipe 12 is the main flow path M, the inner pipe 12
A bypass path B is formed between the outer pipe 15 and the outer pipe 15.

On the other hand, FIG. 7 shows a fifth embodiment of the present invention. In this embodiment, branch holes 16 and 16 are formed on the upstream side and the downstream side of the tail pipe 2, respectively, and the branch holes 16 and 16 are connected to each other. Are connected by a branch pipe 17, a plurality of resistors 14 having passage holes 13 are attached at predetermined intervals inside the branch pipe 17, the inside of the branch pipe 17 serves as a bypass passage B, and the inside of the tail pipe 2 serves as a main passage M. Is. The structure of the other parts of the silencer body 10 is similar to that of the fourth embodiment.

Further, FIG. 8 shows a sixth embodiment of the present invention, in which a resonance preventive body 11 is provided between the exhaust conduit 1 and the silencer body 10. The resonance preventive body 11 itself has a double tube structure including an outer tube 15 and an inner tube 12,
12 is supported by a plurality of supporting pieces 19, 19, ... In a state where no resistor is present between the inner peripheral wall of the outer tube 15 and the main flow path M.
Are formed.

The structure of the inner pipe 12 itself is the same as that of the first embodiment, and therefore the same reference numerals are given and the description thereof is omitted.

The structure of the silencer body 10 is similar to that of the fourth embodiment.

Incidentally, as in the case of the fourth embodiment, the inside of the inner pipe 12 may be the main flow passage M, and the space between the outer pipe 15 and the inner pipe 12 may be the bypass passage B.
Needless to say, the bypass path B may be branched and provided outside as in the fifth embodiment.

Furthermore, as in the seventh embodiment shown in FIG. 9, the silencer body
The inner pipe 12 is positioned by cutting the partition walls 4 and 4 into the inner pipe 10, and a plurality of resistors 14 each having a passage hole 13 are mounted in the inner pipe 12, and these are communicated by the bypass passage B and the intermediate pipes 6 and 6. The narrowed space may be used as the main flow path M.

FIG. 10 shows an eighth embodiment of the present invention,
The resonance preventing body or the exhaust pipe or the inner pipe 12 that is a bypass passage that is attached to the tail pipe is formed into a fin shape in a corrugated form, and the fin-shaped body is an example of a resistor 14, and the inner pipe 12 Small holes 7 are provided on the introduction side and the discharge side, respectively. Since the inner tube 12 and the resistor 14 of this embodiment can be integrally molded, they are easy to manufacture.

Further, since the gas flow rate flowing in the bypass B between the inner pipe 12 and the outer pipe 15 is small because of the resistor 14, there is also an advantage that the outer pipe 15 does not become too hot.

Furthermore, FIG. 11 shows a ninth embodiment of the present invention, in which the inner pipe 12 is formed in a corrugated fin shape, and the outer pipe is further formed.
This is an example in which 15 is formed into a waveform. Inner tube 12, outer tube in this example
Since both 15 are flexible, they have the advantage that engine vibration is not transmitted to the silencer body.

Further, FIG. 12 shows a tenth embodiment of the present invention, in which a wire mesh or a linear resistor 14 is provided between the inner pipe 12 and the outer pipe 15.
Is provided, and has an advantage of easy manufacture.

Further, FIG. 13 shows an eleventh embodiment of the present invention in which each chamber in the silencer body 10 has a large number of passage holes 13 and is larger than the outer diameter of the intermediate conduit 6 in the center. A plurality of resistors 14 each formed of a perforated plate provided with passages are installed.

On the other hand, FIG. 14 shows a twelfth embodiment of the present invention. In this embodiment, a branch hole 16 is provided on the upstream side of the tail pipe 2.
And connect the branch pipe 17 to this branch hole 16
A plurality of resistors 14 each having a passage hole 13 therein are attached at predetermined intervals, the branch pipe 17 is closed at its terminal end, and the inside of the tail pipe 2 is used as a main flow passage M. The structure of the other parts of the silencer body 10 is similar to that of the fifth embodiment. Further, the resistor may be a perforated plate, a spiral plate, a wire mesh, or a linear member, a fibrous sound absorbing member such as glass wool, or the like, as in the above.

The branch hole 16 may be provided in the exhaust conduit 1. This embodiment is particularly effective for long wavelength sound waves.

Further, FIG. 15 shows a thirteenth embodiment of the present invention.

This embodiment is a combination of a sound-absorbing silencer body and a bypass passage. The silencer body 10 is formed of an outer pipe 20, one end of which is connected to the exhaust pipe 1 and the other end of which is connected to the tail pipe 2, and a porous structure. It is composed of an intermediate conduit 21, and a space between the outer tube 20 and the intermediate conduit 21 is filled with a sound absorbing material 22 such as glass wool. In this case, the porous intermediate conduit 21 may be connected to the exhaust conduit 1 and the tail pipe 2 and formed integrally. Further, branch holes 16 and 16 are respectively provided on the upstream side and the downstream side of the tail pipe 2, the branch holes 16 and 16 are connected by a branch pipe 17, and a resistor having a passage hole 13 inside the branch pipe 17.
A plurality of 14 are attached at predetermined intervals, and the inside of this branch pipe 17 serves as a bypass passage B and the inside of the tail pipe 2 serves as a main passage M.

This embodiment is effective for high frequency sound waves of 3 KHZ or more, but it is also possible to mitigate low frequency sound waves by combining a bypass path with a sound absorbing silencer that is less effective at low frequencies. .

The bypass B may be a branch pipe 17 as in the twelfth embodiment shown in FIG.

Next, FIGS. 16 and 17 show a fourteenth embodiment of the present invention in which a bypass passage is located between the outer pipe and the intermediate pipe of the sound-absorbing silencer body. That is, the silencer body 10
Is composed of an outer tube 20 and a porous intermediate conduit 21. In the space between the outer tube 20 and the intermediate conduit 21, a bypass passage B formed by a cylindrical body 24 having a large number of through holes 23 in its peripheral wall is formed. It is located. Furthermore, including the inside of the bypass B,
A space between the outer tube 20 and the intermediate conduit 21 is filled with a sound absorbing material 22 such as glass wool. The intermediate conduit 21 may be integrally formed with the exhaust conduit and the tail lamp as in the thirteenth embodiment.

Further, FIG. 18 shows a fifteenth embodiment of the present invention, in which the silencer body 10 has a triple pipe structure of an outer pipe 20, a porous inner pipe 25, and an intermediate conduit 21 located between the inner and outer pipes, An absorbent material 22 such as glass wool is filled between the outer tube 20 and the inner tube 25, and a sound absorbing material 22 between the intermediate conduit 21 and the inner tube 25 silences high-frequency sound waves, and intermediates the outer tube 20. Bypass B between conduit 21
As for, the sound of low frequency sound is muted.

It should be noted that FIGS. 19 and 20 are spectrum diagrams of sound pressure when the exhaust noise is actually measured at a distance of 45 cm from the end of the tail pipe at an angle of 45 °. Figure 20 is a conventional silencer shown in Figure 21, Figure 19 is a measurement result of the silencer according to the present invention,
In the conventional sound generator, as shown in FIG. 20, there is a frequency range in which the sound pressure becomes extremely large periodically, and it is recognized that a resonance phenomenon occurs. In contrast, the 19th
In the muffler of the present invention shown in the figure, the sound pressure is low as a whole, no resonance phenomenon is recognized, and the muffling is effectively performed. In this measurement, the noise level of the silencer of the present invention was about 6db smaller than that of the conventional one.

(Effects of the Invention) As described above, the silencer of the present invention is based on a completely different principle from the conventional silencer, and the gas flow path from the exhaust pipe to the tail pipe does not reverse the gas flow. As described above, since the exhaust resistance is extremely small, the noise can be effectively eliminated. Further, the structure is extremely simple, there is no risk of failure, and the durability is excellent, which can contribute to energy saving and noise pollution prevention.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a muffler according to a first embodiment of the present invention, FIG. 2 is a vertical sectional side view of another example of a silencer main body, and FIG. 3 is a vertical sectional side view of a second embodiment. FIG. 4 is a vertical sectional side view of the third embodiment, FIG. 5 is a vertical sectional front view of the fourth embodiment, FIG. 6 is a vertical sectional side view of an essential part thereof, and FIG. 7 is a vertical sectional front view of the fifth embodiment. FIG. 8 is a vertical sectional front view of the sixth embodiment, FIG. 9 is a vertical sectional front view of the seventh embodiment, and FIG. 10 is a vertical sectional front view of the eighth embodiment.
FIG. 11 is a vertical sectional view of the ninth embodiment, FIG. 12 is a vertical sectional view of the tenth embodiment, and FIG. 13 is a vertical sectional view of the eleventh embodiment. 14th
FIG. 15 is a vertical sectional view of the twelfth embodiment, FIG. 15 is a vertical sectional view of the thirteenth embodiment, FIG. 16 is a vertical sectional view of the fourteenth embodiment, and FIG. 17 is an arrow LL of FIG. 18 is a vertical sectional view of the fifteenth embodiment. Further, FIG. 19 is a sound pressure spectrum diagram of the silencer according to the present invention,
FIG. 20 is a sound pressure spectrum diagram of a conventional silencer, and FIG. 21 is a vertical sectional front view of an example of the conventional silencer. 1 ... Exhaust pipe, 2 ... Tail pipe, 3 ... Silencer body, 4 ... Partition wall, 5a, 5b, 5c ... Chamber, 6 ... Intermediate pipe, 7 ... Small hole, 9 ... Step section , 10 …… Silencer body, 11
…… Resonance preventive body, 12 …… Inner tube, 13 …… Orifice, 14…
… Resistor, 15… Outer tube, 16… Branch hole, 17… Branch tube,
19 ... Support piece, 20 ... Outer tube, 21 ... Inner tube, 22 ... Sound absorbing material, 23 ... Through hole, 24 ... Cylindrical body, 25 ... Intermediate tube.

Claims (9)

[Claims] 1. An intermediate conduit having an exhaust conduit connected to an exhaust port of an engine or the like, a silencer main body connected to the exhaust conduit, and a tail pipe connected to the silencer main body, the intermediate conduit being installed from the exhaust conduit into the silencer main body. The gas flow path through to the tail pipe is formed in a substantially straight line so that the gas flow does not reverse, and the intermediate conduit has an opening inside the silencer body, and the gas passes inside. A silencer, wherein an inner pipe having a resistor which can be opened and whose both ends are opened is provided in at least a part of the inside of the exhaust pipe, the intermediate pipe, and the tail pipe. 2. An intermediate conduit installed from the exhaust conduit into the muffler body, comprising an exhaust conduit connected to an exhaust port of an engine or the like, a muffler body connected to the exhaust conduit, and a tail pipe connected to the muffler body. The gas flow path through to the tail pipe is formed in a substantially straight line so that the gas flow does not reverse, and the intermediate conduit has an opening in the main body of the silencer. A silencer characterized by shunting from the upstream side of the exhaust gas and connecting a bypass passage that joins the exhaust pipe or tail pipe on the downstream side to the exhaust pipe or tail pipe, and providing a resistor through which gas can pass in this bypass passage. vessel. 3. An intermediate unit installed in a silencer body from an exhaust conduit, the exhaust conduit communicating with an exhaust port of an engine or the like, the silencer body communicating with the exhaust conduit, and the tail pipe communicating with the silencer body. The gas flow path through the conduit to the tail pipe is formed in a substantially straight line so that the gas flow does not reverse, and the intermediate conduit has an opening in the silencer body, A muffler having a plurality of perforated plates serving as resistors inside. 4. An intermediate conduit installed in the muffler body from the exhaust conduit, comprising an exhaust conduit connected to an exhaust port of an engine or the like, a muffler body connected to the exhaust conduit, and a tail pipe connected to the muffler body. The gas passage through the tail pipe is formed in a substantially straight line so that the gas flow does not reverse, and the intermediate conduit has an opening in the silencer body,
A silencer which is branched from an exhaust pipe or a tail pipe, has a terminal end closed, and has a branch pipe provided with a resistor inside. 5. The silencer according to claim 1, wherein the silencer body has a chamber divided into a plurality of sections. 6. An inner pipe or a bypass passage, or a portion of an exhaust pipe or a tail pipe provided with an inner pipe or a bypass passage is formed of a corrugated tube. The silencer described. 7. An intermediate conduit having an exhaust conduit connected to an exhaust port of an engine or the like, a silencer main body connected to the exhaust conduit, and a tail pipe connected to the silencer main body, the intermediate conduit being installed from the exhaust conduit into the silencer main body. The gas flow path through to the tail pipe is formed in a substantially straight line so that the gas flow does not reverse, and the intermediate conduit has an opening in the silencer body, and the intermediate conduit has a porous structure. A silencer, comprising an inner pipe, wherein a sound absorbing material is filled between the intermediate pipe and the inner pipe and between the intermediate pipe and the silencer body. 8. An intermediate conduit having an exhaust conduit connected to an exhaust port of an engine, a silencer main body connected to the exhaust conduit, and a tail pipe connected to the silencer main body, the intermediate conduit being installed from the exhaust conduit into the silencer main body. The gas flow path through the tail pipe to the tail pipe is formed in a substantially straight line so that the gas flow does not reverse, and the intermediate conduit has an opening in the silencer body, and the intermediate conduit has a porous structure. A silencer characterized in that a filling material is filled between the intermediate conduit and the silencer body, a bypass passage is provided, and a resistor is provided in the bypass passage. 9. An intermediate conduit having an exhaust conduit connected to an exhaust port of an engine or the like, a silencer main body connected to the exhaust conduit, and a tail pipe connected to the silencer main body, the intermediate conduit being installed from the exhaust conduit into the silencer main body. The gas flow path through the tail pipe to the tail pipe is formed in a substantially straight line so that the gas flow does not reverse, and the intermediate conduit has an opening in the silencer body, and the intermediate conduit has a porous structure. A bypass passage is provided between the intermediate conduit and the silencer body, the bypass passage being branched from the exhaust pipe or the tail pipe, and the resistor is provided in the bypass passage. Silencer characterized by.